1. Field of the Invention
The present invention relates to an apparatus for finely actuating a glass electrode or the like tool for the purpose of treating a cell to obtain data therefrom by measurements more particularly, the present invention is directed to a finely actuatable apparatus preferably employable for a so-called patch clamping system for measuring the status of a cell while a glass electrode or the like tool is brought in contact with a channel on the cell membrane.
2. Prior Art
As an apparatus for measuring the status of a cell in the field of biotechnology, there is generally known such an apparatus of the type including a glass electrode adapted to be inserted into the interior of a cell to extract biological electricity in the cell via an electrolyte filled in the glass electrode.
However, since a glass electrode or the like tool should be inserted into the interior of a cell, the conventional apparatus has a problem in that the cell is damaged. Accordingly, the cell's live state terminates within a short period of time, with the result that functions of the cell can not be measured for a long period of time.
To solve the foregoing problem, a so-called patch clamp system has been developed in recent years to assure that functions of a cell can be measured for a long period of time. According to the patch clamp system, a glass electrode is aligned with a predetermined channel on the cell membrane to come in contact with it without any need of inserting the glass electrode into the interior of the cell so that the biological electricity of the cell can be measured through the channel for a long period of time. Here, a channel on the cell membrane refers to a position where only necessary materials are introduced into the interior of the cell therethrough and some materials in the interior of the same are discharged to the outside therefrom.
To locate a glass electrode in correct alignment with a channel on the cell membrane, an apparatus for finely actuating the glass electrode is used. The apparatus is intended to finely displace the glass electrode in the vertical direction as viewed from the above (hereinafter referred to as a direction of Y-coordinate), in the lateral direction (hereinafter referred to as a direction of X-coordinate) and in the direction of height (hereinafter referred to as Z-coordinate) by a distance in the order of microns in unit. A conventional apparatus can be generally classified into one of three types, that is, a mechanical type, a hydraulic type or an electrical type. An apparatus of the mechanical type is classified further into two types. One type is such that a plate for the X-coordinate, a plate for the Y-coordinate and a plate for the Z-coordinate are successively jointed to one after another. Each of the plates, for the X-coordinate, the Y-coordinate and the Z-coordinate are thrust against the resilient force of a leaf spring with the use of a lever rod so that a glass electrode mounted on the final plate is finely displaced in the direction of the X-coordinate, in the direction of the Y-coordinate and in the direction of the Z-coordinate.
The other mechanical type is such that a spherical member adapted to eccentrically rotate a tilting operation performed by a lever, thrusts sliders in the direction of the X-coordinate and in the direction of the Y-coordinate. An apparatus of the hydraulic type is so constructed that sliders are finely displaced in the direction of the X-coordinate, in the direction of the Y-coordinate and in the direction of the Z-coordinate by utilizing a plurality of micro-hydraulic cylinders. Of course, an arrangement is made such that a glass electrode is firmly mounted on one of the sliders.
On the other hand, an apparatus of the electrical type is so constructed that a glass electrode is finely displaced in the direction of the X-coordinate, in the direction of the Y-coordinate and in the direction of the Z-coordinate by utilizing step motors.
However, each of the conventional apparatuses as described above has the following problems.
Specifically, an apparatus of the type including a combination of lever rods and a leaf spring with plates operable in the direction of the X-coordinate, in the direction of the Y-coordinate and in the Z-coordinate has a problem in that each of the plates performs arcuate movement but fails to perform fine linear movement. This problem occurs when the plates are thrust in the direction of the X-coordinate, in the direction of the Y-coordinate and in the direction of the Z-coordinate against the resilient force of the leaf springs by operating the lever rods. Since the glass electrode does not perform linear movement but performs arcuate movement in response to actuation of the lever rods in predetermined directions, it is not easy to locate the glass electrode in correct alignment with a predetermined channel on the cell membrane.
Further, an apparatus of the type including a combination of levers for tilting operation with spherical members adapted to eccentrically rotate is so constructed that sliders are displaced in two directions, that is, in the direction of the X-coordinate and in the direction of the Y-direction. Moreover the sliders are thrust under the effect the resilient force of leaf springs on the one side of the direction of the X-coordinate as well as on the one side of the direction of the Y-coordinate. Thus, even on the assumption that the levers are tilted only in the direction of the X-coordinate, a position where the spherical member comes in contact with a contact member when the latter is tilted in the direction of the Y-coordinate is dislocated as they are tilted. The result is that the glass electrode is caused to move finely while scribing a curved track as the levers are tilted, even on the assumption that they are tilted only in the X-direction. This leads to the same problem as mentioned above that they do not perform fine linear movement. Such a problem arises likewise in a case where the levers are tilted only in the Y-direction.
On the other hand, an apparatus of the type using a plurality of micro-hydraulic cylinders has a problem in that the environmental temperature should be kept constant in order to assure that the biological electricity is extracted from a cell for a long period of time, because as an environmental temperature varies, oil in the micro-hydraulic cylinders expands thermally and thereby a glass electrode moves unintentionally to an offset position.
Further, an apparatus of the electrical type has a problem in that due to the fact that an intensity of biological electricity to be extracted from a cell is very weak, exact measurements can not be achieved under the influence of electric induction and magnetic induction caused when step motors are turned on.